Specifics

filename - Filename against which authentication queries are performed

realm - Digest authentication realm

username - Digest authentication user

password - Password for the user of the realm

These parameters must be set prior to calling authenticate().

Identity

The digest authentication adapter returns a Zend_Auth_Result
object, which has been populated with the identity as an array having keys of
realm and username. The respective array
values associated with these keys correspond to the values set before
authenticate() is called.